On a starry night of summer, Sonoko, Ran and Conan are stargazing to find the milky way and the north star when, through her binoculars, Sonoko seemingly witnesses a human's corpse's hand which was lying in the flowerbed. Astonished, she tries to find the place where the corpse was to unmask the criminal. Arrived to the place where she thought the body in the flowerbed was, Sonoko quickly points out that the owner of the building, Hiroto Sasaki, is the culprit to which he says he isn't and that he couldn't be the possible murderer since it wouldn't be possible that she saw the house from the top of the slide. He then suggest they take a rest in his house and production studios. They are served fresh coffee by his assistant Rika Minakami. Then, Sasaki shows her a mannequin arm to ask if it was the arm she saw. She replies by the negative and just then, Sasaki remembers that the house behind his has the same flowerbed but this time, on the rooftop where she could easily have seen it. He says that his house had been larger but he conceded part of his land to his friend Yoshimura who built the house. Yoshimura was Sasaki's college friend just like his wife Nanae. He was the one who had done both flowerbeds since he is a home and garden scape artist. Sasaki then calls his friend to ask him if he could go to his house since Yoshimura was out on business and her wife didn't seem to asnwer the doorbell to which Yoshimura accepts. Since Sasaki had a spare key of the Yoshimura building, the entered and call for Nanae but no one answered. They went to the rooftop but Sonoko found out the earth was not deep enough so a body could be buried. She concludes that the body must have been hidden in the house but everyone (including Conan) just finds her really weird. As the search was finished, Sasaki gets angry and ask them to leave his friend's house since they just wasted his time. They excuse themselves and leave to take a snack at a nearby cafe. Sonoko then headed home alone but saw a ring through a jewelry store window. She then remembered seeing a hand taking off a wedding ring from the body's hand and that it was surely a body since mannequins don't wear rings. She then accidentally pushed the jewelry employee that was folding a panel while she was thinking that Sasaki must have been the culprit since he got angry each time they mentionned a body and was wondering where could it have been hidden. She then tries to put the panel back but put it backwards and then corrects her mistake. She then finds out the truth and yells while running on the streets which scares the employee. At the same time, as Conan walks with Ran, Ran ask Conan if he was thinking about Sonoko. She tells that it would've been easier to find the truth if there was a bridge connecting both houses. Right then, Conan remembers that there was a bridge since when the moon passed upon Sasaki calling his friend, he saw the shadow of a bridge and finds the truth too. He then tells her to run because he found the truth behind the case.

During the lunch break of the National High School Spring Kendo Tournament Heiji is attending, referee Nukitani has his throat slashed, and Nenji, Tsuneyuki, and Akane, who were in the bathroom near the crime scene, are the three suspects in the case. Detective Sato examines their belongings, but she's unable to find the box cutter that is the murder weapon. Based on the suspects' possessions, new testimony from Katsunari, the blind old man at the crime scene, the kendo uniform worn by the culprit, and information from the forensics team, Heiji determines who killed Nukitani and what they used to kill him...